To troubleshoot an air conditioner that isn't blowing air, examine the air filter, and replace the filter if it is dirty. Make sure the thermostat is set to cool, and check the breaker to ensure it is set to the on position. Examine the control board, the thermostat and the wiring that connects the thermostat to the control board, and replace or repair any parts that aren't working properly.
Air conditioning units that have a condensate pump may stop blowing air if the reservoir below the pump fills with water. Examine the condensate pump and reservoir, and replace the pump if water is present. If the fan motor isn't turning or you can't hear the fan, turn the unit off, and examine the unit for signs of damage, such as burned wires. Replace the affected parts as needed.
Ice, frost or water on the unit can cause it to stop working properly. If ice is present, turn the unit off, wait for two hours, and turn the unit back on. Low coolant levels can cause the air conditioner to blow warm air.
If all parts are working properly, contact a heating, ventilating and air conditioning professional for assistance in recharging the coolant levels in the unit. A reset button is present on some HVAC units. If the air conditioner won't start, press the reset button if it is available, and turn the unit on to test it.